Production of alloys containing beryllium



Get. 24, 1939. B. R. 'F. K-[ELLGREN ET AL .9

Y PRODUCTION OF ALLOYS CONTAINING BERYLLIUM Filed July 7, 1956 s Sheets-Sheet 1 INVENTORS' TTORNEY.

Oct. 24, 1939. B, R, ELL REN Er AL mmsoe' PRODUCTION OF ALLOYS CONTAINING BERYLLIUM mm alm 'INVENTORS ATTORNEY.

PATENT} orr cs 2,176,908 PRODUCTION or ALLOYS CONTAINING BERYLLIUM Bengt R. F. Kjellgren Cleveland Heights,

and Charles B. Sawyer, Ohio, assignors to The Brush Beryllium Company, Cleveland, Ohio, a

corporation of Ohio Application July r, 1936, Serial No. 89,362

24 Claims.

- 'Ihisinvention relates to the production of alloys of beryllium with various heavy metals such, for. example; as coppennickel, chromium and iron by thermal reduction of-beryllium ox-,

5 me" with carbon in the presence ofthe other alloying metal of metals. For conveni ce these alloying metals willfbe referred t as heavy metals though we do not Wish to excl de from the 10 num and magnesium in addition to metal. 7

The reduction of the oxide of beryllium with carbon alone has never been accomplished in a commercial way'because the aflinity of beryllium for oxygen is so great and also because its considerable affinity for carbon often results in the production of beryllium carbides. However, it has long been known that the oxides of certain of the light metals such as aluminum and beryl- 20 lium can more easily be reduced with carbon if the reduction is carried out in the presence of a metal that can form an alloy with beryllium at its reduction temperature. --Metals such as those above referred to and which we have designated heavy metals are adapted for this purpose. Thus,

it was a process of this character which the the heavy Cowles brothers practiced fora time for producing aluminum-copper alloys, their process being carried outby passing an electric current 3 through a charge consisting of aluminum oxide.

carbon and copper. Beryllium oxide has a melting point of 2570 C. as compared with the aluminum oxide melting point of 2050 C. and the Cowles procedure has not been found practical for beryllium oxide. However, it was shown by Lebeau that it is possible to reduce beryllium oxide with carbon in the presence of copper and other metals or their oxides. To obtain an intimate mixture, Lebeau precipitated his beryllium and copper together as hydroxides. Suggestions have been made of overcoming the dif- "ficulties which were encountered by Lebeau by controlling the atmospheric conditions of the reduction, or by providing a briquetted supporting'matrix for the reaction components. Nevertheless, prior to our present invention there has been no process, as far as we have been able to learn,- by which the reduction of the oxide of beryllium with carbon, in thepresence of such 0 heavy metals as form alloys with beryllium at the temperature of reduction, can be carried out in a suificiently cheap, efficient and practical way to makethe process commercially useful under present conditions. I 7

Generally speaking; it is the object of ou r invention toprovide such a commercially practicable process and apparatussuitable for its prac tice. Y, I I To this end we have sought to provide a process 60 composition of the alloys the presenr\e of alumiand'apparatus which make possible (1) the heating of the processed materials to high temperatures at relatively low cost, (2). the carrying out of the reduction reaction between the oxide and .the carbon at a rapid rate to save time and labor, (3) a high degree of recovery in the alloy formed, I (4) recovery and re-use of process losses, (5) avoidance of contamination of the charge and product, and (6) repairs and labor 1 costs generally in the operation of the apparatus. 'l'he basic chemical reaction involved in our process isillustrated as follows: (1) 380+ c 2M ==BezM+CO solid solid liquid liquid gas where M is a heavy metal or a mixture of metals and a: may have any value and does not necessarily have the same value at any one moment in the different equations.

Inasmuch as the reaction peratures above 1600" CL, it is evident that in general phases will be present as indicated. Since the reduced beryllium in large part enters the melted heavy metal M, the solution aflimty of M for beryllium is important. This aflinity will be less as the concentration of beryllium increases in liquid M, and presumably less as the temperature of the reaction is increased. Consequently from this point of view it is desirable to carry out the reaction at as low a temperature as possible.

In this process, however, the rate of reaction is also important, and increases as the temperature rises. It is too slow. at 1600 C. and practically we find that-temperatures C. and 2100" takes place at tem- C. are a satisfactory compromise ture's- As temperatures are increased volatilization losses may increase, not only for'beryllium but also for the heavy metal. Consequently, if thesource of heat is an electric are; which has much higher temperatures than those given above, care must be taken so toapply the arc that undue losses do not result.

\ Important accompanying reactions are given below:

solid Solid. liquid liquid gas :eeo+nmc+ 2M =3BezM+C0 solid solid liquid liquid gas between 1800 for heavy metals melting below these tempera-.

action and their products, including carbon monoxide, into effective contact with the solid phases given in any of the Equations (1) to (4) In some cases carbon and beryllium oxide may also be somewhat soluble in the heavy liquid metal M, and if so, will still farther facilitate contact of the components.

From a consideration of Equations (1 to (4) it is apparent that the progress of the main reaction and side reactions will be materially affected by the material of the reaction container or hearth. Thus, if such material is either graphite or beryllium oxide, it can enter directly into the reaction. It is possible that a practically neutral or inertcontainer material exists,

and that a container-formed of it would have advantages. .Atordinary reaction temperatures I we have found that zirconium oxide enters only carbide maybe reached; at which time it is rejected and appears as a solid phase, not neces sarily' as simple beryllium carbide. When such rejected carbide is produced, the operation of the furnace becomes difficult, and in practice-we find that alloys of higher beryllium content tend to produce more carbides especially when such alloys are produced in a graphite container.

On the other hand we=find it distinctly advantageous to operate with a beryllium oxide container especially when producing alloys' tending to form carbides at higher beryllium contents as explained immediately above. a beryllium oxide container, Reaction (4) comes more into play, while Reactions (2) and (.3) are from another.

reduced. The final product is a composite of all the reactions, and it is noted that their 'compara tive rates of progress may be quite difierentone Depending on 'the extent to which graphite or beryllium oxide of the container enters into the reactions, it may be desir able to protect the container composed of the one or the other by having a small excess of carbon or beryllium oxide, respectively, present in the charge. i

The progress of the reaction is easiest, to control with a neutral container, as in this case all the components of the charge can be most easily controlled, from time to time as may be required.

So far as concerns the progress of the reac-' tion we have foundthat it absorbs considerable heat during its progress and may be carried out under any conditions of heating permitting the charge to attain and maintain the necessary temperature for the necessary time, without introducing undesirable gaseous impurities or components into'the reaction zone. Thus the reac= tion has been carried out in a high frequency induction furnace, in a carbon crucible resistance furnace and in an arc furnace, care being taken in each case to supply the necessary heat and to protect the charge from theatmosphere, from moisture and from other-contamination. With reference to contamination it must be noted that the beryllium oxide, employed should obviously In the case of be free'from those impurities which can be reduced and which are-undesirablein the finished metal. with reference to other impurities such as CaO which are'reduced with difliculty and do not necessarily enter the metal, harmful effects due to sintering of the beryllium oxide can nevertheless result. Such sintering may result in slowing up the reaction, and ca'using piling up of the charge within the furnace. Such effect can also be traced to small quantities of silicon dioxide, which, though partially reduced into the metal, can also cause sintering with results like those of CaO. The density of commercial beryllium oxideincreases with increase of impurities therein and in practice we find certain maximum limits of density of beryllium oxide which has which difficulties are encountered in carrying out our process. Our methods of testing for acceptability of beryllium oxide with reference to sinbeen heated to certain temperatures, beyond I tering, will be explained at a later point in the j description. I I

' The hot alloy of heavymetal. and beryllium, as produced by our process, will contain more or less dissolved or admixed impurities such as beryllium carbide, beryllium oxide and carbon monoxide, together with some admixed carbon. These impurities (other than the carbon monoxide) have melting points higher than that of the alloy and we have found that holding the metal above but close to its melting points per-. mits impurities, solid at this temperature, to rise to the surface, whence they maybe skimmed off. Further, since the melting .point of the alloy ismuch'below its temperature of production, and 5 since the solubility of beryllium carbide in the metal at this lower temperature is much less, even to being practically zero in some cases, there often results a practical and cheap method for its complete separationfWe have further discovered that when these skinimings, which are rich in beryllium content, are broken up, they may be in large part returned-to the reduction process, though in their reuse careful allowance should be made for their chemical composition and state of subdivision. i

Holding the metal just aboveits melting point has the effect also of releasing dissolved gases from it, such as carbon monoxide derived from the reaction. The longer the metal is so held, the more complete is removal of dissolved gasesbut the greater is the loss of beryllium due to its ployed such as washing with hydrogen or other.

inert gas, or treatment in a vacuum. I r

During the course of the reaction there is a considerable evolution of fumes consisting of beryllium. oxide more or less admixed with heavy metal. There may be a considerable amount of such fumes they should be recovered and returned to the. process. This source of inefficiency in beryllium processes of this general character seems not to have been appreciated heretofore. I g

In carrying out our process we preferably make .use of a furnace having a reaction chamber of ,reoxidation; Consequently the holding time the pot type and preferably use as a source of a heat for the reduction reaction an electric are,

of finely divided beryllium oxide and carbon with small pieces or fragments of'the heavy metal or oxide of the heavy metal to be alloyed with beryllium. Such a mixture can be prepared with a minimum expenditure of time, labor and ex- ,pense if the-heavy metal is not finely divided. mixture of materials we preferably charge progressively into the reaction zone immediately around the electric are or arcs which are main tained adjacent to the surface of a molten bath. of the alloy produced by the process. Thus we provide a relatively small reaction zone into which the charge is gradually fed and in which the reduction reaction is carried out with a high degree of emciency with resultant deposition of berylliumv into the underlying bath. Simultaneously the particles of the heavy metal, or alloy of heavy metalor a mixture of the heavy metal with oxide, loosely held in the charge, are gradually deposited from the charge and introduced into the surface of the bath so that the heavy metal is constantly added to the upper stratum of the bath, thus avoiding the possibility of its becoming too rich in beryllium with resultant slowing down of the sate of absorption of the beryllium.

- To'make possible the easy progressive charging of the furnace we keep the reaction chamber open to the atmosphere and substantially at atmospheric pressure. At the same time, losses of metal vaporized'by the high temperature of the electric arc and not directly absorbed in the molten bath or charge immediately above'it, are

I minimized by providing a reactionchamber of sufficient depth so that the upper parts of the chamber walls can be maintained cool enough to condense metal vapors rising from the reaction zone and serve to conduct the liquefied vapors downward to the bath in the bottom 'of the chamber. Also losses incident of oxidation of the metals are substantially completely avoided by providing appropriately restricted outlet openings in the upper part of the reaction chamber through which carbon monoxide, generated by the reduction reaction, is constantly issuing so that the chamber is kept effectively filled with carbon monoxide during the operation of the furnace. The said outlet opeings, by reason of their restricted size, also insure thatthe metallic vapors rising to the upper region of the reaction chamber shall contact with the relatively cool wall surfaces and be condensed, with a minimum escape of the metallic vapors through the restricted outlets.

In order that our improved process and ap-' paratus may be clearly understood and successfully used by others, we will now describe in detail procedures and forms of furnace construction which we have found successful, reference being had to the accompanying drawings of the furnace.

In the drawings, Fig. 1 is a vertical sectional view showing one form of furnace suitable for the operation of our process.

Fig. 2 is a fragmentary vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal sectional view on the line 33 of Fig. 1 and showing the body of the furnace in plan.

Fi 4 is .of Fig. 1.

a horizontal section on the line 4-4 in its entirety by the numeral 2. The pot 2 consists of an outer wall section 2 of carbon blocks and a lining section 2 which is formed by ramming a mixture of powdered carbon and pitch and then,coking the rammed material in situ. The pot 2 is heat insulated and supported within the shell I by. a wall 3 of more or less finely di-- vided carbon. The bottom layer 3, which supports the weight of the furnace pot, is preferably formed of a mixture of relatively coarse resistor carbon and finely divided carbon, such as that known to the trade as Norblack, which is low in gaseous content. The side layers or sections 3* of the wall 3 may be formed entirely of the finely divided Norblack, or other suitable heat insulator, such as fiufiy beryllium oxide, or zirconia.

The side walls of thefurnace are carried above the level of the pot 2 in the form of a walled section 4 of suitable material such is sillimanite, beryllium oxide, or other suitable refractory, which rests upon the top wall of thepot 2 but is somewhat thinnner so as to expose a portion of the top wall of the pot and thus form a ledge or shoulder to support a plurality of removable cover plates 5, 5 which are made of graphite, beryllium oxide or other suitable refractory, and are formed with elongated openings 5. We are especially partial to the use of beryllium oxide as a refractory where possible, since its use avoids all possibility of contamination. The sillimanite section 4 of the furnace wall is surroundis preferably covered with a plate 1 of some suitable refractory material such as that known to the trade as Transite and which consists of a mixture of asbestos fiber and cement.

For heating the furnace we make use of one or more carbon arcs, the particular furnace illustrated being designed to operate with two arcs. The two carbon rod electrodes 8, 8 are supported by'suitable water cooled" metal electrode carriers 9, 9 which are fitted with racks l0, I0 and may be slidably supported to be adjusted upward and downward by pinionsll, II. We do not illustrate the electrode supporting and adjusting mechanism fully as it may be of any suitable construction adapted to perform the function-indi cated.

Theelectrode carriers 9, 9 are adapted to have" The electrodes'il, 8 extend downward through the elongated apertures 5 of the cover plates 5 and in operation are adjusted to bring their lower ends at a suitable distance above the bottom of the 'pot or above the bath l3 'of molten metal in the bottom of the pot.

The furnace is provided at its bottom with a third electrode member [4, the main body of which rests upon the inner side of the furnace [4 thereofshell I while downward extension projects through an opening in the said shell. The electrode I4 is preferably water cooled and is adapted to h'ave'a conductor I 5 suitably at 'p ivotally sustained on suitable supports "Giiot shown) so that the furnace can be "tipped to pour out the melt. I

Assuming the availability of a furnace such as hasbeen described above, the next step in preparing for the carrying'out of our process is the preparation of the materials to be charged into the furnace, these materials being the oxide suitably raised again to strike the arcs.

of beryllium, carbon, and the heavy metal with which beryllium is to be valloyed. The temperature at which the furnace will be operated will depend .in part upon the particular heavy metal to be used. The oxide shouldbe sufficiently pure so that it will not sinter to any considerable extent at the operating temperatures. If sintering were permitted to. occur the material fed into the furnace would form more or less into nodules or lumps with or without sticking to the container walls, and thus interfere with the desired operation of the process. This will be more fully apparent from the laterdescription of the mam ner in which the reaction occurs in the furnace.

Pure resistor carbon constitutes a satisfactory form of carbon for use- The heavy metal should be of commercially pure grade in small piecesor fragments. Clean filings, borings, turnings, thinp'unchings and the like are suitable in form, it being unnecessary, in our process, to usethe more costly metal powder. Suitable relative amounts of the three constituent materials are weighed out and introduced into a suitable ball mill in order to finely divide and intimately mix the beryllium oxide and thei carbon. The ball mill may bealined with'such materials as silica, the heavy metal or rubber and, to avoid contamination of the charge, balls formedofthe, same metal as the heavy metal constituent of the charge are preferably em ployed. These balls should be heavy enough to beat the heavy metal fragments. There may be a very slight contamination of the charge mixture from the ball mill lining but we have found that it is not great enough to be objectionable.

The mixture of finely divided oxide and carbon with the heavy metal fragments, as'prepared' in the ball mill, after about three hours of operation, is ready to be charged into the furnace.

In starting the furnace from the cold state in v the carrying out of our process the dry material is at the outset charged into the furnace invery small amounts, the material being introduced through the central part of the cover plate opening 5 between the electrodes 8, 8. When the first small charge has been introduced the electrodes 8, 8 are lowered into contact with the charge and At the outset, because bf the lowtemperature of the furnace, the arcs are unsteady, as indicated by wide fluctuations of the ammeter needles and it is necessary for a time to adjust the electrodes 8, 8 up or down to 'vary the gaps between their lower ends and the charge so as to secure a relatively regions of the arcs. The extremely high tempercarbon monoxide. Thus beryllium'is produced by the reduction of its oxide in the presence ofthe ,andcarbon; We thus effect a gradual'introduction of heavy metal into the upper stratum of the and this is repeated at intervals until the temperature of the furnace has risen to the desired normal operating temperature, .which can readilybe determined .by turning oi the currentand taking the temperature of the glowi charge with an optical pyrometer through th charging hole.

When the furnacev temperature thus determined has reached the desired normal, charges that are lar er, yet quite moderate in size, are intermittentl introduced into the furnace and the operation is continued until the molten material has risen to the point where it becomes desirable to discharge the furnace.

The operation within the furnace in carrying out our process is, webelieve, quite distinctive. The high temperature of the arc melts the small pieces or fragments of the'heavy metal of. the

charge which heavy metal sooner or later settles through the unreduced beryllium oxide and there is thus established a molten'metal bath between. which and the lower ends of the electrodes 8, l the electric arcs extend. Upon this molten bath is sustained the unreduced portion of the loose charge together with some heavy metal which has not settled through it. The action of the arcs causes an agitation of the molten bath and this tends to\jar the smallparticles of the loose charge down upon the surface of the molten bath which is freely exposed under the electrodes and in the ature of the arcs toward which the unreduced materials thus approach is very effective in cansing a rapid reduction-reaction between the carbon and the beryllium oxide with-evolution of molten heavy metal into which beryllium is absorbed. Indeed, inspection of the operation of the furnace indicates that the reduction reaction for the most part occurs at or close to the exposed 40 surface of the molten bath under the arcs.

If the beryllium (or alloy richer in beryllium than is the alloy to be produced) resulting from the reaction were alone introduced intothe top of the molten bath objectionable Stratification of the bath would result. The alloy formed, being lighter than the heavy metal, would concentrate in a top layer or stratum .of the bath and this action would tend seriously to'reduce the absorbing power of the bath for the beryllium. We successfully overcome this difficulty by gradually inbath and in this way counteract the tendencyto the above mentioned concentration and effectively v of thetop exterior furnace structure is minimized. 7

Because of the relatively. deep form of the rea action chamber or furnace pot the walls of the upper part of the chamber are maintained at a temperatures sumoiently low partially to condense vapors of the metal whichhas been vaporized by the direct action of the electric arcs. The vaporized metal thus'liquefied falls back into the charge and eventually into the molten bath. A limited amount of the metallic vapors may escape with the carbon monoxide issuing through the openings around the electrodes but because of the restricted size of these openings the major part of the metallic vapors is caused to contact with the relatively cool top walls of the reaction chamber and is thus condensed and recovered.

If it is desired to maintain'openings in the top of the furnace that would be large enough to permit some outside air to enter and reoxidize some of the reduced beryllium, such re-oxidation and oxidation of the upper graphite parts of the furnace can be overcome by introducing a neutral gas, such as'nitrogen or a reducing gas such as natural gas. We have found the latter very convenient in practice.

As. more and more material is oharg'edinto the furnace and reduced, the volume of the'molten bath of course increases and as its level rises it is necessary to adjust the electrodes 8, 8 upward from time to time so as to maintain the electrical input'and the temperature of the furnace fairly constant. As the level of the molten bath and. the position of the arcs rise in the reaction chamber the temperature of the upper chamber walls tends of course to increaseand it is necessary to stop the operation of the furnace and draw off the alloy formed when the molten bath reaches a level beyond which the top temperatures of the reaction chamber would be too high for safety or for condensation of the metallic vapors formed, with resultant undue metal losses.' In other words. in our process we avoid operating the arcs close enough to the upper walls of the chamber to prevent the latter from performing their va 'por-condensing function. To this end we prefer to use arcs that are short and of relatively low voltage,so that the upper part of the furnace is not overheated. This practice also tends to minimize volatilization of the metals. In the furnace herein described we have satisfactorily used arcs from one-quarter inch to three-quarters inch long and, generally speaking, prefer to use arcs less than one inch long and to efiect desired variation of the power input to the furnace by varying the current.

When the furnace is discharged 9. small amount of molten metal may be retained in the furnace if its operation is to continue or it may be completely emptied and the operation started again as previously described by charging the dry material into the empt chamber.

Our process has been found very advantageous in thepreparation of beryllium-copper alloys and, as furtherillustrating and explaining our invention, we will now describe a suitable and typical procedure for the production of such alloys, employing a furhace such as that illustrated in the drawings in which the diameter of the reaction chamber is 10 inches and the diameter of the carbon rod electrodes 8, 8 is 1 inches. A suitable batch of the dry materials prepared in the ball mill in the manner previously described contains the following:

Pounds v(1) Copper chip s j 200 (2) Berylliumnxidp 29 ll. (3) Electrode carbon (pure resistor carbon) 15 These amounts correspond to the following percentages by weight:

Per cent The amount of carbon used corresponds to an excess of 7.9% over the theoretical amount nec: essary to reduce the beryllium oxide, such exoess being provided to replace carbon losses in the furnace due to oxidation by air. Oxidation by moisture can be minimized by maintaining the materials of the charge in a dry atmosphere prior to their introductionv into the furnace or by heating the mixed materials to moderate temperatures. (150 (Lt-290 C.) before charging them into the furnace. The beryllium oxide employed should be pure. We have found beryllium oxide prepared by the process described in our United States Letters Patent No. 2,018,473 especially well and preferably theoxide should be pure enough i to prevent substantial sintering thereof at the temperature of the reduction reaction as car- 'ried out in the practice of the process.

A very good practical test-for'adequate purity of the beryllium oxide used is its apparent bulk density. after being heated for the first time for a period of ten minutes at a tempxature of 1600 C. in an atmosphere not more strongly'reducing than that of hydrogen. In carrying out this heattreatment, the beryllium oxide is passed through an mesh screen and allowed to fall lightly into -a refractory boat which is to hold it during the heating operation. In Fig. 5 we have shown apt paratus to be used in determining the apparent ratus consists of a sieve i1 comprising frame or side wall I! and standard Tyler screen ll having 20 openings per inch. the wire of the screen having a diameter of 0.0172 inch and the individual screen openings having. an area of 0.0328 square inch. The sieve is supported as shown in a large glass funnel 38 which in turn is suitably supported above a, weighing bottle or cup i Q. The full size dimensions of each piece of the apparatus are indicated in Fig. 5. I

In making the apparent density determination, after heating the specimen at 1600" C. as above described, an amount of the beryllium oxide sulficient to slightly, more than fill the weighing bottle is placed upon the sgreen li and brushed through so as to fall through the funnel, without packing, into the weighing bottle the volume of which, at a height level with its top, is known.

The small excess of beryllium oxide is scraped ofi (without packing) to leave the material even with the bottle top. The weight of the oxide in the weighing'bottle is then determined and the apparent density calculated from the known vol-' ume and the determined weight.

The expression "apparent density as used in this specification, including the claims, in con-' nectionwith the beryllium oxide of our process, is to be understood as meaning the apparent density as determined in the manner above descrlbed.

i For thebest operation of our process the apparent density of the beryllium oxide, determined density of the heat treated material. The appaas above described, should be less than 0.4.. If itis greater than 0.5 the operation of the furnace is unsatisfactory as considerable quantities of sintered beryllium oxide or possibly carbide remain on the bath, causing loss of material and interfering with speedy reduction. The troublesome impurities most frequently encountered in the beryllium oxide are calcium oxide and siliicon oxide, though there maybe others. .Unde- 1o,

composed sulphate may also cause trouble. Calcium oxide should be less than 0.1% in the berylf lium oxide.

As before stated the copper employed need not be powdered, or pulverized, nor in the form of copper oxide precipitated together with beryllium oxide. Not even in its coarser form does it have to be briquetted. We are therefore able'to avoid expense incident to.subdividing and briquetting and can employ industrial metallicby-products where prior processes would not permit of this.

Spherical material of the maximum size that will pass a 25-mesh sieve has a surface to volume ratio of 217 and material in the form of cylinders of the same diameter and a length of about eight times their diameter has a surface to volume ratio of 145. Such copper chips as are employed by us and available at scrap prices, have surface to volume ratios less than 150 and we have successfully used copper shot with a surface to volume ratio (all calculated in inches) as low as 30. Of course anything available commercially varies in its state of subdivision but in general we employ materials having a surface,

to volume ratio, calculated in inches, lying between 150 and 30. The materials can be tested for surface-by placing in contact. with a. dilute acid for a fixed period of time and noting loss to be charged into thereducing furnace."

Assuming that the furnaceis to be started from the cold state, one pound of beryllium oxide, car- 'bon and copper mixture is charged into the bottom of the reaction chamber and the electric arcs are started by contacting the surface of the mixture with the electrodes in the manner previously described. The electrodes 8, 8 are then adjusted as previously described to regulate the arcs as well as possible as the furnace warms up.

After 15 minutes run on the initial charge of one pound another one-pound charge of the mixture is introduced and the operation of the furnace, continued for another 15 minutes. The in- .taken with an optical pyrometer through the troduction of these one-pound charges every quarter hour is continued for about 3 hours when the temperature of the furnace .(molten bath) is charging hole: If thetemperature is found to be below 1825 C. the introduction of small or onepound charges at quarter-hourintervals is con- 'tinued further until the temperature is within the range of 1825 C. to 1850 C., whereupon the size of the charge introduced each quarter hour is increased to 6 pounds. At the same time the. voltage of thefu'rnace is adjusted to approximate- 1y 38 volts, with arcs between V and long ,of'skimmings containing about 6 to as above explained, and this voltage is maintained throughout the remainder 'of the run. Each of the two arcs draws a current of approximately 600 amperes and with such an electric input the furnace continues to operate at a temperature with G-pound ranging from 1850 to 1940, charges introduced at quarter-hour intervals.

The operation of the furnace is continued and when the level of the molten alloy bath has risen until the furnace is approximately two-thirds full the current is turned off and the furnace'dis- (charged by pouring. To permit-this the electrodes 8, 8 are, of course, raised entirely out of the furnace. The molten alloy preferably is poured from the furnace into apivotally mounted transfer pot lined with graphite or carbon from which pot the metal may in turn be poured into molds, or a purifyingcrucible as has been previously indicated.

For purifying beryllium copper alloys as produced by-our process, we employ a crucible of natural flake-graphite and clay, such as is used in the brass industry. The crucibleis heated in a gas-fired furnace, from which it may be lifted by tongs familiar to foundry operators, and transported to the moulds.

The arc furnace charge, at a; temperature of 1800 to 1900 C., is first poured into the transfer pot, with some loss of beryllium due to visible oxidation. The hot metal is quickly cooled down in the transfer pot, as by having 12 to 15 pounds of skimmings of previously purified metal on the bottom of the pot., After pouring into the transfer pot the metal is stirred immediately to dissolve the skimmings and remove dissolved gases. By this procedure the temperature of the hot metal drops to about 1200 C': in about 1 to 2 minutes. The cooled metal is then immediately poured into the graphite-clay crucible maintained,

at 1000-1100" C. in the gas-fired furnace men- 40 tioned above. Coke is now added to protect the surface of the hot metal from oxidation and the '3 metal allowed to stand 30 to 4.5 minutes after which the coke is removed and the metal.

skimmed until the surface is clean. The amount of skimmings varies between 10 and20 pounds per 100 pounds of clean metal. The clean metal is then poured into the molds. By this method metal largely free fromcarbide, oxide and car-' bon is produced. If the metal is stirred effective- 5 lyin the-transfer pot and allowed to cool down to a temperature close to its melting point prac-v tically all dissolved or occluded gases-also are eliminated. I

There is additional loss of beryllium by oxidation all of the time during which the metal re mains in the clay-graphite pot. Accordingly this period should not be longer than is necessary to effect the purification:

Theskimmings as removed from the crucible are a thick mushy mixture of beryllium copper alloy with 'beryllium, oxide and more or less beryllium carbide. These skimmings are broke? 1 up and subdivided as much as possible while st in the mushy state, so that they can be fed back- 5m into the reduction furnace and into' the transfer {pot and their important beryllium content recovered. In one run producing 1040 lb's. of beryllium copper alloy'there were obtained 150 pounds of beryllium content.

After pouring the furnace the electrodes'may be reinserted and a new heat started. We find thatin the normal operation of the furnace described it is poured approximately every 5 hours 15 8 per cent.

quarter-hour intervals is such as .we have found satisfactory with v the furnace described it is to be observed that the rate of feeding of the beryllium oxide, carbon and copper mixture should be regulated so that there is sufiicient time between the introduction of charges for substantially all of the beryllium oxide to be reduced by the carbon and for the alloying of the beryllium with'the copper. If the mixture is fed more rapidly than beryllium oxide is reduced it will cause the beryllium oxide and carbon to ac cumulate unduly in the reaction chamber as the run proceeds and this will cause the alloy formed to be low in beryllium and to contain dissolved carbon and beryllium oxide and will leave beryllium oxide on the surface of the molten bath, causing the metal to pour with diificulty and giving it a mushy consistency as soon as it begins to cool. These effects are especially noticeable when using impure beryllium oxide resulting in greater.v sintering. As has been stated, we have found the quarter-hour intervals between charging to be satisfactory for the furnace described except that the final interval before pouring should be longer to make'sure that the beryllium oxide is fully reduced. On the other hand, it

should be understood that the operation of the furnace should not be continued too long for the individual charges since this tends to cause undue andunnecessary metal loss by volatilizae tion withresultant reduction of the yield realized. It will be understood that by using a reaction chamber of largerdiameter than that described the size of the charges introduced periodicallycan be correspondingly increased. 7 The production capacity of the reaction chamber will, of course, increase with increase of the power input and with increase of the area of the molten metal bath. 7

Operating .our process for the production of beryllium-copper alloy and using the moderate I size furnace described (10" diameter "reaction chamber) we have consistently produced such alloy containing (before purification byskimming) between 4 and 5 per cent. beryllium with a combined beryllium-copper yield of approximately 91%, a beryllium yield from beryllium oxide of a proximately 78% and with an electric current consumption of 55 kilowatt hours per pound of beryllium recovered as .alloy. As will be appreciated by those familiar with the production of beryllium and beryllium alloys, these results constitute a marked advance over all prior practice.

In the practice of our process it is possible to use as a source of beryllium oxide the dross produced in the commercial manufacture of beryllium .bronze from rich or master alloy. The serious loss 'of the beryllium content of such dross may thus be obviated. ,For instance, beryllium-copper alloy containing 4.5% of beryllium may be melted in a crucible with sumcient copper and nickel to produce a final-alloy or bronze containing 2 A of beryllium. During such melting, with the necessary mixing, there is always more or less oxidation of the beryllium, copper and nickel, which oxidized metals appear as dross on the surface of the melt in the crucible. Before pouring into ing'ot moulds this dross mustbe skimmed off, and

is always found to entrain more or less-of the metal itself composing the melt. It is possible to recover this dross in our furnace, as above stated.'

Analysis of one such commercially produced dross gives,the following result:

Two hundred pounds of such dross was mixed in the ball mill as previously described with 12 to 14 pounds of carbon, the amount depending somewhat on the composition. The material thus pro--. duced is fed into our furnace exactly as above described. Such dross charges give a good deal more dust while being reduced than doesthe'regular mixture with pure beryllium oxide. Some sintering also takes place within the furnace, and a considerable amount of non-reacting powder is produced in the furnace, these occurrences necessitating a more frequent cleaning of the furnace, and resulting in a lower yield of beryllium. The recovery ofberyllium in this particular run was about 64 per cent, while the-metal produced contained 3.8 per cent of beryllium. No effort was made to feed back the skimmings though this could .have been accomplished. Also dross may be mixed with our regular chargein carrying out the present process. X

. The above described apparatus for the production of alloys of beryllium and a heavy metal may be advantageously employed "in the production of alloys of aluminum with the heavy metals.

1 295.474, filed September 18, 1939.

While the above described procedure is such as we have found suitable in the practice of our process, it will be understood that the advantages of the inventioncan be more or less realized by using various modifications such as may occur to those skilled in such work or such as specific applications of the process may dictate. The appended claims are intended to indicate the scope of the invention. i

What we claim is:

1. In the method of forming alloys containing berylliurrrand heavy metal by reducing beryllium oxide with carbon in the presence of the heavy metalto produce-the alloy in a molten state,.the steps .of cooling the molten ,metal to a point just above that at which it begins to solidify; holding the metal in such molten state; and skimming oil? impurities which rise to the surface of the metal.

2. The method of forming alloys containing beryllium and heavy metalcapable of alloying with beryllium at a temperature at which the beryllium oxide is reducible with carbon, the said method consisting in introducing a mixture of finely divided beryllium oxide and carbon with pieces of heavy metal into a reaction zone; supplying the requisite heat to said zone to efiect reduction and produce the alloy in a molten state; cooling the molten metal produced to a point 'just above that at which it begins to solidify; holding the metal in suchv molten state; skimming off impurities which rise to the. surface of the metal;

and returning the skim'mings to the reaction zone We do not in the present application claim the v to supply a portion of the beryllium for the reduction. c

3. The method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at a temperature at which the beryllium oxide is reducible with carbon, the said method consisting in introducing into areaction zone a mixture of finely divided carbon and dross skimmed from molten alloy of beryllium and the said heavy-metal; supplying heat to the reaction l zone requisite for the reduction of the dross and the production of molten alloy; cooling the molten metalproduced to a point just above that at which it begins to solidify; holding the metal in such molten state; and skimming off impurities which rise to the surface of the metal. v

4. The method of forming 'alloys containing beryllium and heavy metal capable of alloying with beryllium at a temperature at which beryllium oxide is reducible with carbon, the said method consisting in maintaining in a uitable chamber an electric are adjacent to th urface of a molten bath of alloysuch as it is des ed to form; progressively introducing into the z ne immediately surrounding the are a loose ixture containing finely divided carbon and beryllium oxide of such a degree ofpurity that its apparent density after being heated to 1600 C. for the first, time able chamber an electric arc adjacent to the surface of a molten bath of alloy such as it is desired 'to form; progressively introducing into the zone immediately surrounding the arc a loose mixture containing finely-divided carbon and beryllium oxide of sufficient purity. to prevent substantial sintering of the oxide during the treatment and thereby causing areaction between the oxide and carbon with resultant evolution of carbon monoxide and addition of beryllium to the molten bath; and meanwhile progressively introducingv intmthe top of the said molten bath small pieces of the said heavy metal. I

6. The method of forming alloys containing beryllium and heavy metal capable of alloying therewith at the temperature at which beryllium oxide is reducible with carbon, the said method consisting in maintaining in the bottomof a suitable chamber amolten bath of alloy such as is to be formed; maintaining adjacent to the surface of said bath an electric arc; progressively introducing into the zone immediately surrounding the arca loose mixture of finely divided carbon and beryllium oxide and therebycausing a reaction between the oxide and carbon withla resultant' formation of beryllium and evolution-of carbon monoxide; progressivelyintroducing into the topjof the said molten bath small pieces of the said heavy metal; maintaining-in the said, chamber an atmosphere of carbon monoxide substantially at atmospheric pressure; meanwhile progressively adjusting the arc electrode or electrodes to maintain the relation thereof with the surfaceoLthe molten bath approximately con stant as the surface progressively rises; and intermittently removing molten metal from the said bath so thatthe said are or arcs may be kept;

far enough below the upper partoi the chamber to permit condensation in the upper part -of the chamber of metal vaporized by the heat in the lower part thereof. 1 v 7. The method of forming alloys containing 1 beryllium and copper, the said method comprising introducing into a reaction 'zone heated to a temperature above 1600 C. a loose mixture 'of pieces of copper and finely divided beryllium oxide together with a reducing agent having a temperature of reaction with beryllium oxide above 1600" C., the beryllium oxide employed being sufliciently pure to prevent slnterihg thereof at a temperature of 1500 C.

8. The method of forming alloys containing beryllium and copper, the said method comprising introducing into a reaction zone heated toatemperature above 1600 C. a loose mixture of pieces of copper and finely divided beryllium oxide together with a reducing agent having a temperature. of reaction with beryllium oxide above 1600" (3., the beryllium oxideemployed being of such degree of purity that its apparent density after being heated to 1600 C. for the first time does not exceed 0.4.

9. The method of forming alloys containing beryllium and copper, the said method comprising introducing into a reaction zone heated to a temperature above 1600" C. copper, beryllium oxide and a reducing agent having a temperature of reaction with beryllium oxide above 1600 ciently pure to prevent sintering thereof at 'a temperature of 1500? C.

A 10.- The method'offorming alloys containing beryllium and copper, the said method comprising introducing into a reaction zone heated to a 0., the beryllium oxide employed being sum temperature above 1600 C. copper, beryllium g oxide and a reducing agent having a temperature of reaction with beryllium oxide above 1600 0., the beryllium oxide employedbeing of such degree of purity that its apparent density after being heated to 1600 C. for the first time does not exceed 0.4.-

11. The method of forming alloys containing beryllium and copper, the said method comprising introducing into a reaction zone heated to .a temperatureabove 1600 C. copper, beryllium oxide and a reducing agenthaving a temperature of reaction with. beryllium oxide above ing less than 0.1% of calcium oxide and being 1600" C., the beryllium oxide employed containotherwise sufliciently pure to prevent sintering thereof at a temperature of 1500 C. I I

12. The method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at a temperature at which beryllium oxide is reducible with carbon, the said method consisting'in progressively charging into a reaction zone heated to a temperature above 1600" C. a loose mixture of finely divided beryllium oxide and carbon with pieces of heavy" metal, the said oxide being sufllciently pure to prevent substantial sintering thereof at a.tem-

perature of 1500 C.

13."The method of forming alloys containing beryllium and heavy metal capable ofalloying. with beryllium at a temperature at-which bery1-.

lium oxide is reducible with carbon,. the said method consisting in progressively charging into.

a reaction zone heated to a temperature above .1600" C. aloose mixture of finely divided beryllium oxide and carbon with pieces of heavy metal, "the beryllium oxide being of such a degree of purity that its apparent density after being heated to 1600 c. for the first time does not exceed 0.4.

14. The method oi forming alloys containing beryllium andheavy metal capable of alloying with beryllium at a temperature at which beryllium oxide is reducible with carbon, said method consisting in maintaining a molten bath of alloy such as is to be formed; progresively introducing into a reaction zone heated to a temperature above 1600 C. and disposed adjacent the surface of said bath a loose mixture containing finely divided carbon and beryllium oxide of such a degree of purity that its apparent density after being heated to 1600 C, for the first time does not exceed 0.4; and meanwhile progressively introducing into the top or the said molten bath small pieces of the said heavy metal.

15. The method of forming alloys of beryllium and heavy metal according to claim 14, in which the pieces of the heavy metal used are of such size that their surface to volume ratio does not exceed 150 when the ratio is calculated in terms of inches.

16. The method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at temperatures above 1600 C., thesaid method comprising introducing into a reaction zone heated to a temperature above 1600 C. such heavy metal, beryllium oxide and a reducing agent having a temperature of reactionwith beryllium oxide above 1600 C., the beryllium oxide employed being of such degree of purity that its apparent density after being heated to 1600 C. for the first time is less than 0.5.

17. The method or forming alloys containing beryllium and heavy metal capable of alloying with beryllium at temperatures above 1600 C., the said method comprising introducing into a reaction zone heated to a temperature above 1600 C., a loose mixture of pieces of such heavy metal and finely divided beryllium oxide together with a reducing agent having a temperature or reaction with beryllium oxide above 1600 C., the beryllium oxide employed being of such degree or purity that its apparent density after being heated to 1600 C. for the first time is less than 0.5.

18. The' method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at a temperature at which beryllium oxide is reducible with carbon, the said method consisting in progressively charging into a reaction zone-heated to a temperature above 1600 C. a. mixture of finely divided beryllium oxide and carbon with pieces or heavy metal, the beryllium oxide being of such a degree or purity that its apparent density after being heated to 1600 C. for the first time is less than 0.5.

19. The method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at a temperature at which berylli'um oxide is reducible with carbon, the said method consisting in progressively charging into a reaction zone heated to a temperature above 1600 C. a loose mixture of finely divided beryllium oxide and carbon with pieces of heavy metal, the beryllium oxide being of such a degree of purity that its apparent density after being heated to 1600 C. for the first time is less than 0.5.

. 20. The method of forming alloys containing beryllium and heavy metal capable of alloying lium oxide is reducible with carbon, said method consisting in maintaining a molten bath of alloy such as is to be formed; progressively introducing into a reaction zone heated to a temperature above 1600 C. and disposed adjacent the surface of said bath aloose mixture containing finely divided carbon and beryllium oxide of such a degree of purity that its apparent density after being heated to 1600 C. for the first time is less than 0.5; and meanwhile progressively introducing into the top of the said molten bath small pieces of the said heavy metal.

21. The method of forming alloys containing beryllium and heavy metal capable of alloying with beryllium at a, temperature at which beryllium oxide is reducible with carbon, the said method consisting in maintaining in a suitable chamber an electric are adjacent to the surface of a molten bath of alloy such as it is desired to form; progressively introducing into the zone immediately surrounding the are a loose mixture containing finely-divided carbon and beryllium oxide of such a degree'of purity that its apparent I density after being heated to 1600 C. for the first time is less than 0.5 and thereby causing a reaction between the oxide and carbon with resultant production of beryllium and evolution of carbon monoxide; and meanwhile progressively introducing into the top of the said molten bath small pieces of the said heavy metal.

22. In the method of forming alloys containing beryllium and a heavy metal by reducing beryllium oxide above 1600 C. in the presence of the method consisting in introducing the mixture of finely divided beryllium oxide and carbon with pieces of heavy metal into a reaction zone; supplying the requisite heat to said zone to effect reduction and produce the alloy in a molten state; bringing the alloy to a temperature just above that at which it begins to solidify; skimming oriimpurities which rise to the surface of the metal;

and returning the skimmings to the reaction zone to supply a portion of the beryllium for the reduction.

24. The method of forming alloys containing beryllium and'heavy metal capable of alloying with .beryllium at a temperature at which the beryllium oxide is reducible with carbon, the said method consisting in introducing into a reaction zone a mixture of finely divided carbon and dross skimmed from molten alloy of beryllium and the said heavy metal; supplying heat to the reaction zone requisite for the reduction of the dross and the production of molten alloy; bringing the alloy to a temperature justabove that at which it besins to solidify; and skimming oi! impurities which rise to the surface or the metal.

BENGT R. r'. xanrmm. cmmms B. sawxna. 

